The resignations of the Constitutional Democratic Rally, or RCD, members meant the party's once-powerful central committee dissolved because many of its members in the new caretaker coalition government had quit, Tunisie 7 and Tunisie 21 said.
The resignations came as the government held its first Cabinet meeting since Ben Ali's ouster, said the broadcasters, run by the Tunisian Radio and Television Establishment, or ERTT.
Ben Ali fled into exile in Saudi Arabia Friday after weeks of increasingly violent protests against his regime and alleged corruption involving his family.
The reports did not say what the resignations meant to the plans to hold elections within 60 days.
The Cabinet members' agenda Thursday included discussing a separation between the state and the RCD and a general amnesty, the French newspaper L'Humanite reported.
The general amnesty, announced by Prime Minister Mohamed Ghannouchi Monday, is "the most important point we will consider," a government source told the newspaper before the meeting.
He also said he and interim President Fouad Mebazza had quit the RCD in an attempt to distance themselves from Ben Ali.
Protesters parading outside the former ruling party's headquarters demanded the country break decisively with RCD symbols and structures, The New York Times reported.
The new protests erupted after Mebazza promised a complete "break with the past" in an address carried on state television late Wednesday.
Besides in Tunis, between 3,000 and 4,000 people demonstrated in the town of Gafsa, some 200 miles south of Tunis, and in Kef, 110 miles southwest of the capital, the Voice of America reported.